IFNA1 and rheumatoid arthritis: In the synovium of RA patients, M1 macrophages activated by TLR and IFN signaling produce inflammatory cytokines that promote tissue and cartilage damage and osteoclast differentiation, resulting in bone erosion and joint destruction.14 Meanwhile, activated M2 macrophages produce anti-inflammatory cytokines that contribute to the remission in RA patients.